The present invention relates to system for inhibiting an islanding condition from occurring. More particularly, the present invention relates to a system and method for inhibiting an islanding condition from occurring in an engine driven generator connected to an electrical grid.
Microturbine engines are relatively small and efficient sources of power. Microturbines can be used to generate electricity and/or to power auxiliary equipment such as pumps or compressors. When used to generate electricity, microturbines can be used independent of the utility grid or synchronized to the utility grid. In general, microturbine engines are limited to applications requiring 2 megawatts (MW) of power or less. However, some applications larger than 2 MWs may utilize a microturbine engine.
In many applications, microturbine engines are used to supply power for a local load that is simultaneously connected to an electrical grid (i.e., a utility grid). When connected to the grid, it is important to monitor the system for islanding conditions. Islanding exists when the microturbine engine provides power to the local load with the electrical grid connection severed at some point. This condition can be problematic, as the microturbine engine may not be able to react to sudden load changes or may not be able to provide a sudden increase in demand without the support of the electrical grid. As such, an undesirable trip may occur severing all of the power being supplied to the local load. Therefore, it is desirable to detect islanding conditions and to take steps to isolate the local load or remedy the islanding condition when it is detected.
While many islanding detection schemes are known, most have difficulty detecting islanding conditions that arise when the microturbine output is closely matched with the local load.